Systems and methods for increasing the effectiveness of digital pre-distortion in electronic communications

ABSTRACT

Various embodiments of communication systems and methods in which the communication system is operative to find, record, and use sets of pre-distortion parameters in conjunction with a pre-distortion procedure, in which each set of pre-distortion parameters is operative to specifically counter distortions produced in a power amplifier by a specific combination of level of input signal power and level of analog gain associated with a transmission path of the communication system. In some embodiments, there is a modulator, a transmission chain, a distortion analysis mechanism, and a pre-distortion mechanism, operative to analyze and modify signals so as to counter signal distortion.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.61/974,920, filed Apr. 3, 2014, which is hereby incorporated byreference herein in its entirety.

BACKGROUND

Digital Pre-Distortion (“DPD”) is a basic element of communications,including both wireless and wireline communication systems. It is usedto increase the effectiveness and the efficiency of power amplifiers,particularly in determining system inputs to result in acceptable outputpower. In traditional communications, output power is modified byaltering the input power from a modulator, or by altering the gain levelof a communication transmission chain, or by altering both the inputpower and the gain level to the degree that a change in one parameter isexactly offset by a corresponding and opposite change in the otherparameter.

SUMMARY

Described herein are electronic communication systems and methods tomanage and improve the DPD process resulting in maximum output powerwith minimal signal distortion by considering changes in both an inputpower level and a transmission chain gain.

One embodiment is a communication system operative to managepre-distortion procedures. In one particular embodiment, the systemincludes a transmission chain comprising a power amplifier, in which thetransmission chain is associated with a level of analog gain that isconfigurable by the communication system. Also in this particularembodiment, there is a modulator operative to feed the transmissionchain with a transmission signal having a level of power that isconfigurable by the communication system. One level of transmissionsignal power may occur in a first state of operation of the system, anda different level of transmission power may occur in a second state ofoperation of the system. Also in this particular embodiment, thecommunication system is operative to find, record, and use sets ofpre-distortion parameters in conjunction with a pre-distortionprocedure, in which each said set of pre-distortion parameters isoperative to specifically counter distortions produced in the poweramplifier by a specific combination of said level of power and saidlevel of analog gain. For example, a particular set of parameters XY maybe operative to specifically counter distortions produced by thecombination of X-level of input power and Y-level of transmission chaingain.

One embodiment is a method for managing pre-distortion procedures in acommunication system. In one particular embodiment, a communicationsystem determines a first set of transmission parameters associated witha transmission chain belonging to the communication system, in which thefirst set of transmission parameters includes at least (i) a first levelof power associated with a first transmission signal feeding thetransmission chain, and (ii) a first level of analog gain as applied bythe transmission chain to the first transmission signal. Also in thisparticular embodiment, the communication system finds a first set ofpre-distortion parameters associated with a pre-distortion procedureoperative to counter distortions produced, in conjunction with the firstset of transmission parameters, in a power amplifier belonging to thetransmission chain. Also in this particular embodiment, thecommunication system applies the pre-distortion procedure using thefirst set of pre-distortion parameters, and in that way counters all orat least some of the distortion in the output signal.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments are herein described, by way of example only, withreference to the accompanying drawings. No attempt is made to showstructural details of the embodiments in more detail than is necessaryfor a fundamental understanding of the embodiments. In the drawings:

FIG. 1A illustrates one embodiment of a wireless communication systemwith two receiver chains processing two signals;

FIG. 1B illustrates one embodiment of a wireless communication systemwith two receiver chains processing one communication signal with aninformation payload and one communication signal for purposes ofmonitoring and testing, in which the signal with information payload hasbeen duplicated at the receiver;

FIG. 2A illustrates one embodiment of a wireless communication systemwith two receiver chains processing one communication signal with aninformation payload and one communication signal for purposes ofmonitoring and testing distortions introduced by a power amplifier, inwhich the signal for monitoring and testing has passed through anattenuator;

FIG. 2B illustrates one embodiment of a signal being transmitted by atransmitter through a power amplifier, in which the signal has beenpre-distorted by insertion of an inverse distortion in order to counterat least in part some of the distortion characteristics of the poweramplifier;

FIG. 3 illustrates one embodiment of a wireless communication systemwith two receiver chains processing one communication signal with aninformation payload and one communication signal for purposes ofmonitoring and testing, in which the signal with information payload hasbeen duplicated at the receiver;

FIG. 4 illustrates one embodiment of a receiver interface that may bedigital, and that includes an analog-to-digital converter operative toconvert a first signal that is analog into a digital form;

FIG. 5 illustrates one embodiment of a receiver and a receiver interfacethat have been implemented in a digital-signal-processor;

FIG. 6 illustrates one embodiment of a method by which a wirelesscommunication system may seamlessly dual-use a receiver chain forreceiving incoming transmissions and for other signal sensing purposes;

FIG. 7 illustrates one embodiment of method by which a wirelesscommunication system may dual-use a receiver chain for determiningdistortion characteristics of a power amplifier and for receivingincoming transmissions with information payload;

FIG. 8A illustrates one embodiment of a wireless communication system aclipping mechanism and a filter for a first iteration of clipping asignal;

FIG. 8B illustrates one embodiment of a wireless communication system aclipping mechanism and a filter for a second iteration of clipping asignal;

FIG. 8C illustrates one embodiment of a wireless communication system aclipping mechanism and a filter for a third iteration of clipping asignal;

FIG. 9A illustrates one embodiment of a wireless communicationsub-system with a filter for out-of-band signal filtering;

FIG. 9B illustrates one embodiment of a wireless communicationsub-system with a filter and an interpolator for out-of-band signalfiltering;

FIG. 10A illustrates one embodiment of a wireless communicationsub-system with a decimation mechanism and a clipping mechanism;

FIG. 10B illustrates one embodiment of a wireless communicationsub-system with a zero-padding mechanism and a clipping mechanism;

FIG. 11A illustrates one embodiment of a clipping mechanism and a filterat the microprocessor level;

FIG. 11B illustrates one embodiment of a clipping mechanism and a filterat the DSP level;

FIG. 12 illustrates one embodiment of a polar clipping mechanism;

FIG. 13 illustrates one embodiment of a lookup table for determining aclipping level of a wireless transmission;

FIG. 14 illustrates one embodiment of a method by which a wirelesscommunication system may reduce the peak-to-average power ratio of awireless transmission by an iterative clipping scheme;

FIG. 15A illustrates one embodiment of a wireless communication systemin a first state of operation, in which a certain configurable powerlevel and a certain configurable transmission chain gain level areinputted to produce a signal with a particular output power;

FIG. 15B illustrates one embodiment of a wireless communication systemin a second state of operation, in which a certain configurable powerlevel and a certain configurable transmission chain gain level areinputted to produce a signal with a particular output power, whereineither the input power level, or the input gain level, or both, is orare different from the inputs in the first state of operation;

FIG. 16 illustrates one embodiment of a lookup table recording aplurality of system states in which each system state includes an inputpower level, an input gain level, and one or more pre-distortionparameters associated with such input levels of power and gain;

FIG. 17A illustrates one embodiment of a wireless communication systemin a first state of operation, including a distortion analysis mechanismthat derives one or more pre-distortion parameters from the analysis ofdistortions in an output signal, and including also a pre-distortionmechanism operative to execute a pre-distortion procedure on an inputtransmission signal;

FIG. 17B illustrates one embodiment of a wireless communication systemin a second state of operation, including a distortion analysismechanism that derives one or more pre-distortion parameters from theanalysis of distortions in an output signal, and including also apre-distortion mechanism operative to execute a pre-distortion procedureon an input transmission signal;

FIG. 18A illustrates one embodiment of two processors, in which amodulator is implemented in the first processor and a pre-distortionmechanism is implemented in the second processor;

FIG. 18B illustrates one embodiment of two digital-signal-processors, inwhich a modulator is implemented in the first digital-signal-processorand a pre-distortion mechanism is implemented in a seconddigital-signal-processor;

FIG. 19 illustrates one embodiment of a communication systemtransmitting a base-band transmission signal, including an up-converteroperative to up-convert the base-band transmission signal into atransmission frequency associated with a power amplifier, and includingalso an antenna operative to transmit wirelessly an output signalproduced by the power amplifier in conjunction with the base-bandtransmission signal; and

FIG. 20 illustrates one embodiment of a method by which a communicationsystem may manage pre-distortion procedures.

DETAILED DESCRIPTION

As used herein, “dual-use” is a process in which a receiver chainalternates, according to some scheme, between receiving signals withinformation payloads and receiving other information signals forpurposes of signal monitoring or improving the quality of signals.

As used herein, a “radio-frequency switching fabric” is hardware,software, or a combination of hardware and software that is capable ofswitching the reception of a radio receiver chain between a signal withinformation payload and a different signal.

As used herein, “inverse distortion” is the process of inserting a kindof distortion into a radio signal to offset, at least in part, the knowndistortion characteristics of a transmitter, a power amplifier, or someother hardware through which a radio signal may pass.

As used herein, “maximal-ratio-combining”, sometimes abbreviated as“MRC”, is one or more techniques employed as a method for diversitycombining of radio signals in which the signals of the various channelsare added together to improve the quality of the resulting combinedsignal.

As used herein, “MIMO” is an acronym for amultiple-input-multiple-output communication configuration, which iswell known in the art.

As used herein, “pre-clipping” is a method by which an initial inputsequence of modulated data of a wireless transmission is processed priorto clipping procedure. Pre-clipping may be associated with a decimationmechanism, or with a zero-padding mechanism by way of example.

As used herein, “DPD” is an acronym for “digital pre-distortion”, whichis a description that may be applied to a structure that determines orcounters distortion characteristics in an output signal, or adescription that may be applied to a method by which distortioncharacteristics in an output signal are determined or countered.

As used herein, “memory configuration” is a lookup table that has beenstored in a memory. The lookup table includes two or more records, inwhich each record has at least a given input power level and a giveninput transmission chain gain, plus the pre-distortion parametersassociated with those particular input power levels and transmissionchain gain.

FIG. 1A illustrates one embodiment of a wireless communication system100 with two receiver chains 103 a and 103 b processing two signals 301a and 301 b respectively. FIG. 1A shows a wireless communication system100, including a receiver 101 connected to and receiving signals from areceiver interface 102. The receive interface 102 is connected to andreceives signals 301 a, 301 b from multiple receiver chainsrespectively, here marked as 103 a and 103 b, but there may be three ormore such receiver chains. The receiver chains 103 a and 103 b in termare connected to and receive signals from a radio-frequency switchingfabric 105, which is connected with and receives signals from multipleantennas, here 109 a and 109 b. It will be understood that there is aseparate antenna for each receiver chain, here shown as antenna 109 acommunicatively connected to receiver chain 103 a, and antenna 109 bcommunicatively connected to receiver chain 103 b, but there may bethree or more sets of antennas and receiver chains. Each antennareceives the same transmission, here 301, and the signals 301 a, 301 bassociated with transmission 301 are transported through the wirelesscommunication system 100 until they are combined at receiver 101 usingany kind of signal processing techniques to enhance the quality of thereceived signals. Transmission 301 may be an incoming wirelesstransmission.

FIG. 1B illustrates one embodiment of a wireless communication systemwith two receiver chains processing one communication signal with aninformation payload and one communication signal for purposes ofmonitoring and testing, in which the signal with information payload hasbeen duplicated at the receiver. The state of wireless communicationsystem 100 depicted in FIG. 1B is different from the state of wirelesssystem 100 depicted in FIG. 1A, in several respects. First, in FIG. 1B,the radio switching fabric 105 has switched the signal received byreceiver chain 103 b, such that the signal received by receiver chain103 b is not signal 301 a received at 109 a, nor signal 301 b receivedat 109 b, but rather a third signal 399 that is totally different fromsignals 301 a, 301 b. Second, in FIG. 1B, this third signal, 399, isconveyed by the wireless communication system 100 through receiver chain103 b, to receiver interface 102. Signal 399 may be analyzed on severalparameters, and the results of such analysis may be used is severalways. Third, in FIG. 1B, the receiver interface 102 duplicates thesignal 301 a received at antenna 109 a and conveyed through receiverchain 103 a, and conveys this duplicated signal 301 a-dup to receiver101. At substantially all times during which the communication system isoperating for reception of transmission 301, receiver 101 receiveseither two signals 301 a and 301 b, or two signals 301 a and 301 a-dup.As described herein, receiver chain 103 b is operating in dual-mode,sometimes conveying communications 301 b from antenna 109 b, andsometimes conveying a third signal 399 from the radio-frequencyswitching fabric 105.

FIG. 2A illustrates one embodiment of a wireless communication systemwith two receiver chains processing one communication signal with aninformation payload and one communication signal for purposes ofmonitoring and testing distortions introduced by a power amplifier, inwhich the signal for monitoring and testing has passed through anattenuator. FIG. 2A differs from FIG. 1B in several respects. First, inFIG. 2A, there is an additional transmitter 201 that is transmitting asignal. Second, in FIG. 2A the signal transmitted by transmitter 201travels through a power amplifier 202, which amplifies the transmissionsignal but in so doing may introduce distortions due to imperfects inamplifier 202. Third, in FIG. 2A the signal passing through poweramplifier 202 then passes through an attenuator 203 which attenuates thesignal. The attenuated signal 399-t-a passes through the radio-frequencyswitching fabric 105 to receiver chain 103 b, and then to receiverinterface 102. The signal 399-t-a, which becomes signal 399 at receiverinterface 102, may be analyzed for distortion characteristics, andactions may be taken to counter-act such distortion, as shown in FIG. 2Bbelow.

FIG. 2B illustrates one embodiment of a signal being transmitted by atransmitter through a power amplifier, in which the signal has beenpre-distorted by insertion of an inverse distortion in order to counterat least in part some of the distortion characteristics of the poweramplifier. In FIG. 2B, transmitter 201 transmits a modified signal399-2, in that the modified signal has had inserted into it inversedistortion to counteract, at least in part, the distortions oftransmitter 201 or of power amplifier 202 as determined in the analysisof signal 399-t-a at receiver interface 102. Modified signal 399-2 isnow transmitted by transmitter 201, amplified by power amplifier 202,and will continue through the wireless communication system 100.

FIG. 3 illustrates one embodiment of a wireless communication systemwith two receiver chains processing one communication signal with aninformation payload and one communication signal for purposes ofmonitoring and testing, in which the signal with information payload hasbeen duplicated at the receiver. FIG. 3 is different from FIG. 2A inthat in FIG. 3 there is no transmitter 201 or power amplifier 202 orattenuator 203, but rather radio-switching fabric 105 has switched thesignal received by antenna 109 b from transmission 301 to transmission309 that is different from transmission 301. It will be understood thattransmission 309 may be a different frequency than the frequency for301, or may be a different time slice from the time slice oftransmission 301, or may be a different code/standard from thecode/standard of transmission 301, or may be some combination ofdifferent frequencies, time slices, and codes/standards. Thetransmission 309, also referred to as an incoming wireless transmission,received at antenna 109 b is conveyed through radio-switching fabric 105to receiver chain 103 b, and then to radio interface 102 in the form ofsignal 399. There may be multiple reasons for switching a transmissionfrom 301 to 309. For example, the wireless communication system 100 maywish to determine if a transmission band represented by transmission 309is occupied with traffic, and if not, whether communication traffic maybe placed on that band. For example, the wireless communication system100 may wish to determine if there is possible interference withtransmission 301 from transmission 309, and if so, to determine how suchinterference may be reduced or avoided.

FIG. 4 illustrates one embodiment of a receiver interface that may bedigital, and that include an analog-to-digital converter operative toconvert a first signal that is analog into a digital form. FIG. 4 showsone possible embodiment for the duplication of signal 301 a. In FIG. 4,first receiver chain 103 a receives signal 301 a, and sends it toreceiver interface 102. Receiver interface 102 includes ananalog-to-digital converter 102AD, which converts signal 301 a fromanalog into digital. When signal 301 a is then duplicated and sent toreceiver 101 as 301 a-dup, it is duplicated and sent as a digital ratherthan an analog signal. In other embodiments, signal 301 a would remainin analog form, but this would require receiver interface 102 toduplicate analog signal 301 a and then send it, in analog form.

FIG. 5 illustrates one embodiment of a receiver and a receiver interfacethat has been implemented in a digital-signal-processor. FIG. 5 showsreceiver interface 102 and receiver 101, that have been implemented in aDSP 107, which is one way by which the receiver interface 102 andreceiver 101 may be implemented and structured.

One embodiment is a wireless communication system 100 operative toseamlessly dual-use a receiver chain 103 b for receiving incomingtransmissions and for other signal sensing purposes. In one specificembodiment, the system 100 includes receiver 101, a first receiver chain103 a associated with a first antenna 109 a, and a second receiver chain103 b associated with a second antenna 109 b. Also in this specificembodiment, the receiver 101 is operative to process a first signal 301a received via the first receiver chain 103 a and the first antenna 109a, together with a second signal 301 b received via the second receiverchain 103 b and the second antenna 109 b, thereby enhance reception ofat least one incoming wireless transmission 301 associated with thefirst 301 a and second signals 301 b. Also in this specific embodiment,the wireless communication system 100 is operative to utilise the secondreceiver chain 103 b, during at least one period of the incomingwireless transmission 301, for reception of a third signal 399 notassociated with the incoming wireless transmission 301, thereby makingdual-use of the second receiver chain 103 b, and consequently making thesecond signal 301 b unavailable in the receiver 101 for enhancementduring the at least one period. Also in this specific embodiment, thewireless communication system 100 is further operative, during the atleast one period, to substitute the second signal 301 b with aduplication 301 a-dup of the first signal 301 a, in compensation for theunavailability of the second signal 301 b in the receiver 101, andwithout any knowledge of said receiver 101 regarding such utilizationrequiring said substitution.

In an alternative embodiment to the system just described, the wirelesscommunication system 100 further includes a receiver interface 102operative to perform the duplication of signal 301 a and compensationfor the loss of signal 301 b.

In one variation of the alternative embodiment just described, furtherthe receiver interface 102 is digital and includes an analog-to-digitalconverter 102AD operative to convert the first signal 301 a into adigital form. In this variation, the receiver 101 is also digital,thereby enabling duplication of signal 301 a and compensation for lossof signal 301 b to be made at the digital level.

In one configuration of the variation just described, further thereceiver 101 and the receiver interface 102 are implemented in adigital-signal-processor 107.

In a second variation of the alternative embodiment described above, thewireless communication system 100 also includes a power amplifier 202having certain signal distortion characteristics, a radio-frequencyattenuator 203, and a radio-frequency switching fabric 105. Also in thissecond variation, the wireless communication system 100 is furtheroperative to transmit a first transmission 399-t via the first poweramplifier 202, resulting in the first transmission 399-t having adistortion associated with the signal distortion characteristics. Alsoin this second variation, the wireless communication system 100 isfurther operative to use the radio-frequency switching fabric 105 andthe radio-frequency attenuator 203 to bypass the second antenna 109 b,and to inject, during the at least one period of said incoming wirelesstransmission 301, an attenuated version 399-t-a of said firsttransmission 399-t having the distortion, into the second receiver chain103 b, wherein said attenuated version 399-t-a becomes the third signal399. Also in this second variation, the wireless communication system100 is operative to determine the first signal distortioncharacteristics of the power amplifier 202, via analysis of thedistortion present in the third signal 399 received via said secondreceiver chain 103 b.

FIG. 6 illustrates one embodiment of a method by which a wirelesscommunication system may seamlessly dual-use a receiver chain forreceiving incoming transmissions and for other signal sensing purposes.In step 1011, a wireless communication system 100 enhances, in areceiver 101, reception of at least one incoming wireless transmission301, by processing (i) a first signal 301 a associated with the incomingwireless transmission received via a first receiver chain 103 a and afirst antenna 109 a, and (ii) a second signal 301 b associated with theincoming wireless transmission received via a second receiver chain 103b and a second antenna 109 b. In step 1012, the wireless communicationsystem 100 utilises the second receiver chain 103 b, during at least oneperiod of the reception, for receiving a third signal 399 not associatedwith the incoming wireless transmission 301, thereby dual-using thesecond receiver chain 103 b, and consequently making the second signal301 b unavailable in the receiver 101 for enhancing during the at leastone period. In step 1013, the wireless communication system 100compensates, during the at least one period, for the unavailability ofthe second signal 301 b in the receiver 101, by substituting to thereceiver 101 the second signal 301 b with a duplication 301 a-dup of thefirst signal 301 a, thereby making the receiver 101 unaware of theutilisation requiring said substitution.

In a first alternative embodiment to the method just described, thewireless communication system 100 transmits 201, a first transmission399-t via a power amplifier 202 having certain signal distortioncharacteristics, resulting in the first transmission 399-t having adistortion associated with the first signal distortion characteristics.Also in this alternative embodiment, the wireless communication system100 injects, during the at least one period of the reception, anattenuated version 399-t-a of the first transmission 399-t having thedistortion, into the second receiver chain 103 b, wherein the attenuatedversion 399-t-a becomes the third signal 399, thereby bypassing thesecond antenna 109 b and facilitating said utilization requiring saidsubstitution. Also in this first alternative embodiment, the wirelesscommunication system 100 determines the signal distortioncharacteristics of the power amplifier 202, by analyzing the distortionpresent in the third signal 399 received via said second receiver chain103 b.

In a first variation of the first alternative embodiment just described,further the enhancement is adversely affected as a result of theduplication during the at least one period. In order to reduce or evenminimize these adverse impacts, the wireless communication system 100reduces the length of the at least one period to a necessary minimum. Inone configuration of the first variation just described, the necessaryminimum duration of the at least one period is at least 100microseconds, but not longer than 10 milliseconds, thereby allowingsufficient time for the wireless communication system 100 to analyze thedistortion present in the third signal received via the second receiverchain 103 b during the at least one period.

In a second variation of the first alternative embodiment describedabove, the wireless communication system 100 further operates in afrequency-division-duplex mode, such that at least most of thetransmitting of the first transmission 399-t occurs substantiallysimultaneously with the reception of at least one incoming wirelesstransmission 301, and such that the transmitting is done at a firstfrequency, and the reception is done at a second frequency.

In one configuration of the second variation just described, further thewireless communication system 100 configures the second receiver chain103 b to operate in the second frequency during the enhancement. Also insuch configuration, the wireless communication system 100 configures thesecond receiver chain 103 b to operate in the first frequency during theutilization of the second receiver chain 103 b.

In a second alternative embodiment to the method described above,further the incoming wireless transmission 301 belongs to a firstfrequency band. Also in this second alternative embodiment, the wirelesscommunication system 100 receives, during the at least one period of thereception, via the second receiver chain 103 b, the third signal 399associated with a second wireless transmission 309 (FIG. 3) belonging toa second frequency band, thereby facilitating monitoring of said secondfrequency band.

In one variation of the second alternative embodiment just described,further the enhancement is adversely affected during the at least oneperiod, as a result of the duplication of signal 301 a. Therefore, toreduce the adverse effect on the enhancement, the wireless communicationsystem 100 keeps the at least one period to a necessary minimum.

In one configuration of the variation just described, further thenecessary minimum is at least one millisecond, but not longer than 10milliseconds, thereby allowing sufficient time for the monitoring of thesecond frequency band during the at least one period.

In a third alternative embodiment to the method described above, furtherthe enhancement is associated with maximal-ratio-combining. Also in thisthird alternative embodiment, the receiver 101 combines the first 301 aand second signals 301 b using maximal-ratio-combining techniques,thereby enhancing a signal-to-noise ratio associated with the incomingwireless transmission 301.

In a fourth alternative embodiment to the method described above,further the enhancement is associated with spatial-multiplexing. Also inthis fourth alternative embodiment, receiver 101, usingspatial-multiplexing reception techniques, decodes at least twotransmission streams from the first 301 a and second signals 301 b,thereby enhancing reception rates associated with the incoming wirelesstransmission 301.

In one variation of the fourth alternative embodiment described above,further the first 103 a and second receiver chains 103 b are parts of amultiple-input-multiple-output communication configuration.

In a fifth alternative embodiment to the method described above, furtherthe at least one period associated with the utilisation is essentiallyperiodic and is kept short relative to periods associated with theenhancement.

In one variation of the fifth alternative embodiment described above,the at least one period associated with the utilisation is shorter thanthe periods associated with the enhancement by a factor of between100,000 and 10,000,000.

FIG. 7 illustrates one embodiment of a method by which a wirelesscommunication system may dual-use a receiver chain for determiningdistortion characteristics of a power amplifier and for receivingincoming transmissions with information payload. In step 1021, awireless communication system 100 transmits a first transmission 399-tvia a first power amplifier 202 having certain signal distortioncharacteristics. The result is that the first transmission has thedistortion associated with the distortion characteristics of the poweramplifier 202. In step 1022, the wireless communication system 200injects an attenuated version 399-t-a, of the first transmission 399-thaving the distortion, into a second receiver chain 103 b belonging tothe communication system 101. In step 1023, the wireless communicationsystem 100 determines certain signal distortion characteristics of thepower amplifier 202, by analyzing the distortion of the attenuatedversion 399-t-a of the first transmission 399-t received via the secondreceiver chain 103 b as signal 399. In step 1024, the wirelesscommunication system receives, via the second receiver chain 103 b, anincoming transmission 301 for decoding by said communication system 100,thereby dual-using the second receiver chain 103 b for both (i)determining the first signal distortion characteristics, and (ii)receiving the incoming transmission 301.

In a first alternative embodiment to the method just described, furtherthe wireless communication system 100 pre-distorts 399-2 a secondtransmission intended for transmission via the power amplifier 202,using the determination of the first signal distortion characteristics.Also in this embodiment, the wireless communication system 100 transmitsthe second transmission 399-t-2 pre-distorted, via the power amplifier202, thereby at least partially countering the signal distortioncharacteristics of the power amplifier 202.

In a second alternative embodiment to the method described above,further the first transmission 399-t is a radio-frequency transmission,and the second receiver chain 103 b is a radio-frequency receiver chain.

In one variation of the second alternative embodiment just described,further the wireless communication system 100 couples the poweramplifier 202 with the second receiver 103 b chain prior to theinjection, using a first radio-frequency coupling mechanism comprisingthe attenuator 203 and the radio-frequency switching fabric 105, therebyfacilitating the injection.

In one configuration of the variation just described, further thewireless communication system 100 releases the coupling prior to thereception of the incoming transmission 301, thereby facilitating thereception of said incoming transmission 301.

This description presents numerous alternative embodiments. Further,various embodiments may generate or entail various usages or advantages.For example, using the radio-frequency switching fabric 105 to switchsignals in receiver chain 103 b allows dual-use of receiver chain 103 b,which may reduce the overall amount of hardware required by the wirelesscommunication system 100.

FIG. 8A illustrates one embodiment of a wireless communication system400 a clipping mechanism and a filter for a first iteration of clippinga signal. A sequence of modulated data 411-a is inputted as a signalinto a clipping mechanism 401. The clipping mechanism 401 has been setat first clipping level 411-CL-a, and clips the signal according to thisfirst level. The clipped signal of modulated data is outputted as 412-a,and is then passed through a filter 402, which executed out-of-bandsignal filtering, and outputs the signal 413-a as a first-level clippedand filtered sequence of modulated data. In some embodiments, thissignal 413-a would now be sent to an up-converter and a power amplifier(not shown in FIG. 8A). In some embodiments, this signal 413-a is sentback into the clipping and filtering system, as explained in FIG. 8Bbelow.

FIG. 8B illustrates one embodiment of a wireless communication system400 a clipping mechanism and a filter for a second iteration of clippinga signal. The clipped and filtered sequence of modulated data 413-a fromFIG. 8A is now fed into the system as new signal 411-b. Sequence ofmodulated data 411-b is inputted as a signal into the clipping mechanism401. The clipping mechanism 401 has now been set at second clippinglevel 411-CL-b, and clips the signal according to this second level. Theclipped signal of modulated data is outputted as 412-b, and is thenpassed through the filter 402, which executes out-of-band signalfiltering, and outputs the signal 413-b as a second-level clipped andfiltered sequence of modulated data. In some embodiments, this signal413-b would now be sent to an up-converter and a power amplifier (notshown in FIG. 8B). In some embodiments this signal 413-b is sent backinto the clipping and filtering system, as explained in FIG. 8C below.

FIG. 8C illustrates one embodiment of a wireless communication system aclipping mechanism and a filter for a third iteration of clipping asignal. The clipped and filtered sequence of modulated data 413-b fromFIG. 8B is now fed into the system as new input 411-c. Sequence ofmodulated data 411-c is inputted as a signal into the clipping mechanism401. The clipping mechanism 401 has now been set at third clipping level411-CL-c, and clips the signal according to this third level. Theclipped signal of modulated data is outputted as 412-c, and is thenpassed through the filter 402, which executed out-of-band signalfiltering, and outputs the signal 413-c as a third-level clipped andfiltered sequence of modulated data. In some embodiments, this signal413-c would now be sent to an up-converter and a power amplifier (notshown in FIG. 8C). In some embodiments, this modulated signal will passthrough fourth, fifth, or additional rounds of clipping and filtering.

FIG. 9A illustrates one embodiment of a wireless communicationsub-system with a filter 402 for out-of-band signal filtering. As shownin FIG. 9A, filter 402 has outputted third level clipped and filteredsequence of data 413-c. In this embodiment shown, three iterations haveproduced a signal 413-c which is sufficiently good so that it need notbe sent for a fourth iteration, but rather is sent as 413-c-TR to anup-converter and a power amplifier (not shown in FIG. 9A), from where itwill be transmitted.

FIG. 9B illustrates one embodiment of a wireless communicationsub-system with a filter 402 and an interpolator 403 for out-of-bandsignal filtering. The sequence of data 413-c is inputted into aninterpolator 403, which further conditions the data with interpolationto produce signal 413-c-TR ready to be sent to an up-converter and apower amplifier (not shown in FIG. 9B), after which the amplified signalwill be transmitted.

FIG. 10A illustrates one embodiment of a wireless communicationsub-system with a decimation mechanism 404 and a clipping mechanism 401.In FIG. 10A, before sequence of data 411-a is sent into a clippingmechanism 401 at a first level of clipping 411-CL-a, the sequence ofdata 411-a passes through a decimation mechanism 404, which conditionsthe data to create a decimated sequence of data. 411-a, in decimatedform, is then sent to clipping mechanism 401 for a first level clipping.

FIG. 10B illustrates one embodiment of a wireless communicationsub-system with a zero-padding mechanism 405 and a clipping mechanism401. In FIG. 10B, before sequence of data 411-a is sent into a clippingmechanism 401 at a first level of clipping 411-CL-a, the sequence ofdata 411-a passes through a zero-padding mechanism 404, which conditionsthe data to create a zero-padded sequence of data. 411-a, in zero-paddedform, is then sent to clipping mechanism 401 for a first level clipping.

FIG. 11A illustrates one embodiment of a clipping mechanism and a filterat the microprocessor level. In FIG. 11A, the clipping mechanism 401 isa processor, and the filter 402 is entirely different processor, asshown. In alternative embodiments, the clipping mechanism 401 and thefilter 402 may be co-located on one processor.

FIG. 11B illustrates one embodiment of a clipping mechanism and a filterat the DSP level. In FIG. 11A, a first processor 401DSP is a digitalsignal processor (“DSP”) and includes the clipping mechanism 401. InFIG. 11A, a second processor is a digital signal processor 402DSP, andincludes the filter. In alternative embodiments, the clipping mechanism401 and the filter 402 are co-located on one DSP.

FIG. 12 illustrates one embodiment of a polar clipping mechanism401-polar. In FIG. 12, the clipping mechanism, which was 401 in priorfigures, is now a polar clipping mechanism 401-polar, which executespolar clipping. In this embodiment, non-polar clipping, which wasexecuted by clipping mechanism 401, does not occur, and is replaced bypolar clipped executed by 401-polar.

FIG. 13 illustrates one embodiment of a look-up table 406 fordetermining a clipping level of a wireless transmission. In FIG. 13, alliterations, where it is only the first level 411-CL-a, or the first twolevels 411-CL-a and 411-CL-b, or the first three levels 411-CL-a and411-CL-b and 411-CL-c, or four or more iterations, are based on thelook-up table 406. In this particular embodiment, every clipping levelis a function, at least in part, on its iteration number as first,second, third, fourth, or any subsequence number.

One embodiment is a wireless communication system 400 (FIG. 8A)operative to reduce iteratively a peak-to-average power ratio ofwireless transmissions. In one particular form of such embodiment, thereis a clipping mechanism 401 (FIG. 8A, 8B, 8C) operative to (i) receivesequences of modulated data 411-a, 411-b, 411-c, (ii) clip each sequenceof modulated data using a settable clipping level, and (iii) outputclipped sequences of modulated data 412-a, 412-b, 412-c associated withthe sequences of modulated data, respectively. Also in this particularform of such embodiment, there is a filter 402 operative to (i) receivethe clipped sequences of modulated data 412-a, 412-b, 412-c, (ii) filterout-of-band signals produced by the clipping mechanism 401 out of theclipped sequences of modulated data, and (iii) outputclipped-and-filtered sequences of modulated data 413-a, 413-b, 413-cassociated with the clipped sequences of modulated data, respectively.Also in this particular form of such embodiment, the wirelesscommunication system 400 is operative to use the clipping mechanism 401and the filter 402 iteratively, such that at least some of theclipped-and-filtered sequences of modulated data are fed back into theclipping mechanism 401, thereby constituting at least some of thesequences of modulated data as explained hereunder. As one example,first level clipped-and-filtered sequence 413-a is fed back and becomessecond level clipped-and-filtered sequence 411-b, and second levelclipped-and-filtered sequence 413-b is fed back and becomes third levelclipped-and-filtered sequence 411-c. Also in this particular form ofsuch embodiment, the wireless communication system 400 is set up, foreach iteration of clipping and filtering, a clipping level that isunique and different than other clipping levels associated with otheriterations. For example, (i) clipping level 411-CL-a is set-up for afirst iteration associated with 411-a, 412-a, 413-a, (ii) clipping level411-CL-b is set-up for a second iteration associated with 411-b, 412-b,413-b, and (iii) clipping level 411-CL-c is set-up for a third iterationassociated with 411-c, 412-c, 413-c.

In a first alternative embodiment to the wireless communication system400 just described, the wireless communication system 400 is furtheroperative to use a last of the clipped-and-filtered sequences ofmodulated data as a sequence for wireless transmission 413-c-TR (FIG.9A) by the wireless communication system 400. In FIG. 8C, the lastclipped-and-filtered sequence of modulated data is shown as 413-c, whichis the sequence after three levels of clipping and filtering, but it isunderstood that there may be four or more levels of clipping andfiltering, or only two levels of clipping and filtering, and the outputof the last level will become the sequence for wireless transmission.

In a variation to the first alternative just described, the wirelesscommunication system 400 further includes an interpolation mechanism 403(FIG. 9B) operative to interpolate the last of said clipped-and-filteredsequences of modulated data 413-c, thereby producing the sequence forwireless transmission 413-c-TR (FIG. 9B) by said wireless communicationsystem 400. Again, the last sequence is shown as 413-c, but it may be alater sequence after four or more levels of clipping and filtering, or aprevious sequence after two levels of clipping and filtering.

In a second alternative embodiment to the wireless communication system400 described above, the wireless communication system 400 is furtheroperative to feed (FIG. 8A) a first of said sequences of modulated data411-a as an initial input to the clipping mechanism 401, therebytriggering the iterative clipping and filtering operation.

In a first variation to the second alternative just described, thewireless communication system 400 further includes a decimationmechanism 404 (FIG. 10A) operative to produce the first of the sequencesof modulated data 411-a as an initial input to the clipping mechanism401.

In a second variation to the second alternative described above, thewireless communication system 400 further includes a zero-paddingmechanism 405 (FIG. 10B) operative to produce the first sequence ofmodulated data 411-a as an initial input to the clipping mechanism 401.

In a third alternative embodiment to the wireless communication system400 described above, further the clipping mechanism 401 is a firstprocessor 401P (FIG. 11A) operative to perform the clipping.

In a first configuration to the variation just described, further thefirst processor 401P and the second processor 402P are the same oneprocessor 401P. In such configuration, the clipping mechanism and thefilter are part of the same processor 401P.

In a second configuration to the variation to the third alternativeembodiment described above, further the first processor 401P and thesecond processor 402P are digital signal processors, 401DSP and 402DSP,respectively (FIG. 11B).

In a fourth alternative embodiment to the wireless communication system400 described above, further the clipping 401 mechanism is a polarclipping mechanism 401-polar (FIG. 12).

In a fifth alternative embodiment to the wireless communication system400 described above, further each of the clipping levels, excluding thefirst clipping level 411-CL-a, is higher and thus more relaxed thanprevious clipping levels, thereby reducing distortions. For example,411-CL-c is higher than 411-CL-b, and 411-CL-b is higher than 411-CL-a.

FIG. 14 illustrates one embodiment of a method by which a wirelesscommunication system may reduce the peak-to-average power ratio of awireless transmission by an iterative clipping scheme. In step 1031, awireless communication system 400 applies, on a sequence of modulateddata 411-a, a peak-to-average power ratio reduction scheme, where suchscheme includes (i) a clipping procedure, executed by a clippingmechanism 401, followed by (ii) out-of-band signal filtering, executedby a filter 402, wherein the clipping procedure is set to a firstclipping level 411-CL-a. Application of clipping and filtering at thefirst clipping level results in a first level clipped-and-filteredsequence of modulated data 413-a. In step 1032, the wirelesscommunication system changes the setting of the clipping mechanism 401from the first clipping level 411-CL-a to a second clipping level411-CL-b. In step 1033, the wireless communication system again appliesthe peak-to-average power ratio reduction scheme, except now the schemeis applied to the first-level clipped and filtered sequence of modulateddata 413-a, where sequence 413 a is fed back to clipping mechanism 401as 411-b. After a second level clipping and filtering, the result is anenhanced clipped-and-filtered sequence of modulated data 413-b, which isbetter optimized for transmission by said wireless communication system.Similarly, a third level clipping and filtering will result in sequenceof modulated date 413-c, and subsequent levels of clipping and filteringwill result in a higher sequence of modulated data, such as 413-d (notshown) after a fourth level of clipping and filtering, or 413-e (notshown) after a fifth level of clipping and filtering. The wirelesscommunication system 400 is iterative, such that there may be two levelsof clipping and filtering, or any number of levels greater than two.

In a first alternative embodiment to the method just described forreducing iteratively the PAPR, further the changing of the clipping andfiltering level, and the applying again, is repeated iteratively untilreaching a first criterion. Further, each iteration of changing theclipping and filtering level, and applying clipping and filtering again,is associated with a unique clipping level. For example, the firstiteration is associated with level 411-CL-a, the second iteration isassociated with level 411-CL-b, and the third iteration is associatedwith level 411-CL-c.

In a first variation to the first alternative method embodiment justdescribed, further the first criterion is a predetermined and fixednumber of iterations.

In a second variation to the first alternative method embodimentdescribed above, further the first criterion is crossing below a firstthreshold of out-of-band signal power.

In a third variation to the first alternative method embodimentdescribed above, further the first clipping level 411-CL-a, the secondclipping level 411-CL-b, and each of the other unique clipping levels411-CL-c and any subsequent level, are determined based on a look-uptable 406 and as a function of iteration number.

In a fourth variation to the first alternative method embodimentdescribed above, further the second clipping level 411-CL-b is higherthan the first clipping level 411-CL-a by a fixed amount of decibels,and each of the unique clipping levels is higher than unique clippinglevel of previous iteration by this same fixed amount of decibels.

In a second alternative embodiment to the method described above forreducing iteratively the PAPR, further the second clipping level411-CL-b is predetermined and fixed.

In a third alternative embodiment to the method described above forreducing iteratively the PAPR, further the second clipping level411-CL-b is higher than said first clipping level 411-CL-a by apredetermined amount of decibels, thereby making the second clippinglevel more relaxed than said first clipping level, thereby reducingdistortions.

In a variation to the third alternative method embodiment justdescribed, further predetermined amount of decibels is between 0.3decibel and 1 decibel.

In a configuration to the variation to the third alternative methodembodiment just described, further said predetermined amount of decibelsis approximately 0.5 decibels.

In a fourth alternative embodiment to the method described above forreducing iteratively the PAPR, further the clipping procedure comprisesclipping the sequences of modulated data 411-a, 411-b, and 411-c.

In a variation to the fourth alternative method embodiment justdescribed, further the clipping is a polar clipping.

In a fifth alternative embodiment to the method described above forreducing iteratively the PAPR, further decimating, by a decimationmechanism 404, an initial input sequence of modulated data (not shown),thereby producing the sequence of modulated data 411-a which is adecimated version of the initial input sequence of modulated data, andin this way matching a rate of the initial input sequence of modulateddata to a desired rate of signal at clipping.

In a first variation to the fifth alternative method embodiment justdescribed, further the decimating is operative to keep a sampling rateover signal bandwidth ratio within a predetermined range.

In a configuration to the variation to the fifth alternative methodembodiment just described, further the predetermined range is betweenapproximately 3 and approximately 5.

In a second variation to the fifth alternative method embodimentdescribed above, further interpolating, by interpolator 403, FIG. 9B,the enhanced clipped and filtered sequence of modulated data 413-c,thereby producing 413-c-TR ready for transmission, and as resultreturning to the rate of initial input sequence (not shown) of modulateddata. It is understood that if there are more than three levels ofclipping and filtering, then the final sequence of modulated data willnot be 413-c, but rather 413-d (not shown) or some higher level sequenceof modulated data.

In a sixth alternative embodiment to the method described above forreducing iteratively the PAPR, further zero-padding, by a zero-paddingmechanism 405, FIG. 10B, an initial input sequence (not shown) ofmodulated data, thereby producing the sequence of modulated data 411-awhich is a zero-padded version of the initial input sequence ofmodulated data, and a result matching a rate of the initial inputsequence of modulated data to a desired rate of clipping.

In variation to the sixth alternative method embodiment just described,further the zero-padding is operative to keep a sampling rate oversignal bandwidth ratio within a predetermined range.

In a configuration to the variation to the sixth alternative methodembodiment just described, further the predetermined range is betweenapproximately 3 and approximately 5.

In a seventh alternative embodiment to the method described above forreducing iteratively the PAPR, further the wireless transmission system400 transmitting, as signal 413-c-TR, FIG. 9A, FIG. 9B, the enhancedclipped and filtered sequence of modulated data 413-c. It is understoodthat if there are more than three levels of clipping and filtering, thenthe sequence of modulated data to be transmitted as signal 413-c-TR willnot be 413-c, but rather 413-d (not shown) or another signalcorresponding to the number of iterations of the clipping and filteringlevel.

In an eighth alternative embodiment to the method described above forreducing iteratively the PAPR, further the sequence of modulated data411-a conforms to a wireless transmission standard selected from a groupconsisting of LTE, WiMAX, and WiFi.

In a variation to the eighth alternative method embodiment justdescribed, further the modulation is selected from a group consistingof: BPSK, QPSK, 16-QAM, 64-QAM, and 256-QAM.

FIG. 15A illustrates one embodiment of a wireless communication system500 in a first state of operation, in which a certain configurable powerlevel 599-power-level and a certain configurable transmission chain gainlevel 599-gain-level are set to produce an output signal 599-t with aparticular output power. In FIG. 15A, there is a transmission signal 599having a configurable or changing power level 599-power-level. Amodulator 504 feeds the transmission signal 599 into a transmissionchain 501. The transmission chain 501 applies a configurable gain level599-gain-level to the transmission signal 599. The system includes alsoa power amplifier 502, which receives and amplifies the transmissionsignal 599, thereby producing the output signal 599-t.

FIG. 15B illustrates one embodiment of a wireless communication system500 in a second state of operation, in which a certain configurablepower level 598-power-leve and a certain configurable transmission chaingain level 598-gain-level are set to produce an output signal 598-t witha particular output power, wherein either the input power level598-power-level, or the input gain level 598-gain-level, or both, is orare different from the inputs in the first state of operationillustrated in FIG. 15A, such that an output signal 598-t is producedthat has an output power that may be different from or similar to theoutput power of the output signal 599-t produced in the first state ofoperation FIG. 15A. The second state illustrated in FIG. 15B includesthe modulator 504, the transmission chain 501, and the power amplifier502, which appear also in the first state illustrated in FIG. 15A.

FIG. 16 illustrates one embodiment of a lookup table recording aplurality of system states in which each system state includes an inputpower level, an input gain level, and one or more pre-distortionparameters associated with such input levels of power and gain. FIG. 16illustrates one embodiment of a memory configuration 520, which is anelectronic memory holding the data comprising a lookup table. The lookuptable consists of various records. Shown in FIG. 16 are first record 521and second record 522, but it is understand that there may be three ormore such records. Each record includes one set of at least two inputs,and one set of outputs. In the first record 521, there is a first statepower level 599-power-level and a first state transmission chain gainlevel 599-gain-level, which together comprise a first set of inputtransmission parameters in the form of an index 521-i. The first record521 includes also a first record entry 521-r, which includes a first set599PDPS of pre-distortion parameters which were previously found tospecifically counter distortions produced by a specific combination ofthe first state of power level 599-power-level and the first state ofanalog gain level of the transmission chain 599-gain-level. In thesecond record 522, there is a second state power level 598-power-leveland a second state transmission chain gain level 598-gain-level, whichtogether comprise a second set of input transmission parameters in theform of an index 522-i. The second record 522 includes also a secondrecord entry 522-r, which includes a second set 598PDPS ofpre-distortion parameters which were previously found to specificallycounter distortions produced by a specific combination of the secondstate of power level 598-power-level and the second state of analog gainlevel of the transmission chain 598-gain-level. Additional records,which may be part of the lookup table but which are not illustrated inFIG. 16, would also include an index of input transmission parametersand a record or pre-distortion parameters found to specifically counterdistortions produced by the specific combination of the power level andanalog gain level for the particular state of the system represented bythe record.

FIG. 17A illustrates one embodiment of a wireless communication system500 in a first state of operation, including a distortion analysismechanism 506 that derives one or more sets of pre-distortion parameters599PDPS from the analysis of distortions in an output signal 599-t, andincluding also a pre-distortion mechanism 505 operative to execute apre-distortion procedure on an input transmission signal 599. In FIG.17A, an input transmission signal 599 at a given power level599-power-level, passes through a modulator 504 and then apre-distortion mechanism 505 operative to execute a pre-distortionprocedure on the signal 599, after which the signal 599 is sent to atransmission chain 501 with a configurable gain level 599-gain-level,and then to a power amplifier 502 which amplifies the signal 599 andproduces an output signal 599-t. The power amplifier 502 may be part ofthe transmission chain 501. Output signal 599-t is analyzed by adistortion analysis mechanism 506 operative to derive a set ofpre-distortion parameters 599PDPS. The input power level 599-powerlevel, the transmission gain level 599-gain-level, and the set ofpre-distortion parameters 599PDPS, for this state of the communicationsystem 500, are added to the memory configuration 520 in FIG. 16 tocreate a new record.

FIG. 17B illustrates one embodiment of a wireless communication system500 in a second state of operation, including a distortion analysismechanism 506 that derives one or more sets of pre-distortion parameters598PDPS from the analysis of distortions in an output signal 598-t, andincluding also a pre-distortion mechanism 505 operative to execute apre-distortion procedure on an input transmission signal 598. In FIG.17A, an input transmission signal 598 at a given power level598-power-level, passes through a modulator 504 and then apre-distortion mechanism 505 operative to execute a pre-distortionprocedure on the signal 598, after which the signal 598 is sent to atransmission chain 501 with a configurable gain level 598-gain-level,and then to a power amplifier 502 which amplifies the signal 598 andproduces an output signal 598-t. The power amplifier 502 may be part ofthe transmission chain 501. Output signal 598-t is analyzed by adistortion analysis mechanism 506 operative to derive a set ofpre-distortion parameters 598PDPS. The input power level 598-powerlevel, the transmission gain level 598-gain-level, and the set ofpre-distortion parameters 598PDPS, for this state of the communicationsystem 500, are added to the memory configuration 520 in FIG. 16 tocreate a new record.

FIG. 18A illustrates one embodiment of two processors 501P and 502P, inwhich a modulator 504 is implemented in the first processor 501P and apre-distortion mechanism 505 is implemented in the second processor502P. Although FIG. 18A illustrates and embodiment with two processors501P and 502P, it is understood that the modulator 504 and thepre-distortion mechanism 505 may be implemented in a single processor.Although FIG. 18A shows a direct connection between first processor 501Pand second processor 502P, it is understood that intervening components,or products, or communication pathways, may stand between firstprocessor 501P and second processor 502P, although the two processors501P and 502P are part of the same general communication system 500illustrated in other figures.

FIG. 18B illustrates one embodiment of two digital-signal-processors501DSP and 502DSP, in which a modulator 504, not shown in FIG. 18B, isimplemented in the first digital-signal-processor 501DSP, and apre-distortion mechanism 505, not shown in FIG. 18B, is implemented in asecond digital-signal-processor 501DSP. Although FIG. 18A illustratesand embodiment with two digital-signal-processors 501DSP and 502DSP, itis understood that the modulator 504 and the pre-distortion mechanism505 may be implemented in a single digital-signal-processor. AlthoughFIG. 18BA shows a direct connection between firstdigital-signal-processor 501DSP and second digital-signal-processor502DSP, it is understood that intervening components, or products, orcommunication pathways, may stand between first digital-signal-processor501DSP and second digital-signal-processor 502DSP, although the twodigital-signal-processors 501DSP and 502DSP are part of the same generalcommunication system 500 illustrated in other figures.

FIG. 19 illustrates one embodiment of a communication system 500transmitting a base-band transmission signal 599. The system includes amodulator 504 that modulates the base-band transmission signal, and atransmission chain 501 that transmits a wireless output signal 599-t-w.The transmission chain 501 includes an up-converter 503 operative toup-convert the base-band transmission signal 599 into a transmissionfrequency associated with a power amplifier 502, the power amplifier 502then amplifies the signal to create an output signal 599-t, and antenna509 operative to wireless transmit 599-t-w the output signal 599-t fromthe amplifier 502.

One embodiment is a communication system 500 operative to managepre-distortion procedures. In one specific embodiment, the system 500includes a transmission chain 501 that includes a power amplifier 502,and in which the transmission chain 501 is associated with a level ofanalog gain 599-gain-level or 598-gain-level that is configurable by thecommunication system 500. Also in this specific embodiment, the system500 includes a modulator 504 operative to feed the transmission chain501 with a transmission signal 599 or 598, where the power level599-power-level or 598-power-level is configurable by the communicationsystem. It is noted that configuring power level 599-power-level or598-power-level by system 500 may be done directly by digitally scalingsignal 599 or 598, or it can be done indirectly by a changing demand fordata resources by client devices served by system 500. In onenon-limiting example, a first state transmission signal 599 isconfigured to have a first level of power 599-power-level, and a secondstate transmission signal 598 is configured to have a second level ofpower 598-power-level. Also in this specific embodiment, thecommunication system 500 is operative to find, record, and use sets ofpre-distortion parameters 599PDPS or 598PDPS in conjunction with apre-distortion procedure, wherein each set of pre-distortion parameters599PDPS or 598PDPS is operative to specifically counter distortionsproduced in the power amplifier 502 by a specific combination of thelevel of power 599-power-level or 598-power-level, and the level ofanalog gain of the transmission chain 501, 599-gain-level or598-gain-level, respectively. In one non-limiting example, set ofpre-distortion parameters 599PDPS is operative to specifically counterdistortions produced by the combination 599-power-level and599-gain-level, and set of pre-distortion parameters 598PDPS isoperative to specifically counter distortions produced by thecombination 598-power-level and 598-gain-level.

In a first alternative to the system 500 described above, the system 500further includes a memory configuration 520 operative to facilitaterecording and extraction of the sets of pre-distortion parameters599PDPS and 598PDPS, in which each set of pre-distortion parameters inassociation with a specific combination of the level of power and thelevel of analog gain.

In a variation of the first alternative just described, further thememory configuration 520 includes at least a first 521 and a second 522record, in which the first record 521 includes at least (i) a firstindex entry 521-i and (ii) a first record entry 521-r. The first indexentry 521-i describes a combination of a first power level599-power-level and a first analog gain level 599-gain-level. In onenon-limiting example a first power level 599-power-level is 5 dBm and afirst analog gain level 599-gain-level is 40 dB. The first record entry521-r describes a first set of pre-distortion parameters 599PDPSpreviously found to specifically counter distortions produced by aspecific combination of the first level of power 599-power-level and thefirst level of analog gain 599-gain-level. Also in this variationembodiment, the second record 522 includes at least (i) a second indexentry 522-i and (ii) a second record entry 522-r. The second index entry522-i describes a combination of a second power level 598-power-leveland a second analog gain level 598-gain-level. In one non-limitingexample a second power level 598-power-level is OdBm and a second analoggain level 599-gain-level is 47 dB. The second record entry 522-rdescribes a second set of pre-distortion parameters 598PDPS previouslyfound to specifically counter distortions produced by a specificcombination of the second level of power 598-power-level and the secondlevel of analog gain 598-gain-level.

In a second alternative to the system operative to manage pre-distortionprocedures described above, the system further includes adistortion-analysis mechanism 506 operative to derive the sets ofpre-distortion parameters 599PDPS and 598PDPS, by analyzing distortionsin an output signal, 599-t and 598-t, respectively, produced by thepower amplifier 502 in conjunction with the specific combinations oflevel of power 599-power-level and 598-power-level and the level ofanalog gain 599-gain-level and 598-gain-level, respectively.

In a variation of the second alternative system described above, furtherthe distortion-analysis mechanism 506 is operative to derive a first ofthe sets of pre-distortion parameters 599PDPS that specifically counterdistortions produced by a specific combination of a first of level ofpower 599-power-level and a first level of analog gain 599-gain-level.

In a particular configuration of the variation of the second alternativesystem, described above, further the distortion-analysis mechanism 506is operative to derive a second set of pre-distortion parameters 598PDPSthat specifically counter distortions produced by a specific combinationof a second level of power 598-power-level and a second level of analoggain 598-gain-level.

In a third alternative to the system operative to manage pre-distortionprocedures described above, the system further includes a pre-distortionmechanism 505 operative to execute the pre-distortion procedure on theinput transmission signal 599 or 598.

In a variation of the third alternative system described above, thesystem further includes at least a first processor 501P and a secondprocessor 502P, wherein the modulator 504 is a digital modulatorimplemented in the first processor 501P, the transmission signal is adigital base-band transmission signal generated in the digital modulator504, and the pre-distortion mechanism 505 is a digital pre-distortionmechanism 505 implemented in the second processor 502P.

In a first possible configuration of the variation to the thirdalternative system described above, the first processor 501P and thesecond processor 502P are a same processor.

In a second possible configuration of the variation to the thirdalternative system described above, the first processor 501P and thesecond processor 502P are digital-signal-processors 501DSP and 502DSP,respectively.

In a fourth alternative to the system operative to manage pre-distortionprocedures described above, further the transmission signal 599 is abase-band transmission signal, and the transmission chain 501 includesalso an up-converter 503 operative to up-convert the base-bandtransmission signal 599 into a transmission frequency associated withthe power amplifier 502.

In a variation of the fourth alternative system described above, thetransmission chain 501 further includes an antenna 509 operative totransmit wirelessly 599-t-w an output signal 599-t produced by the poweramplifier 502 in conjunction with the transmission signal 599.

FIG. 20 illustrates one embodiment of a method by which a wirelesscommunication system 500 may manage pre-distortion procedures. In step1041, a communication system 500 determines a first set of transmissionparameters associated with a transmission chain 501 belonging tocommunication system 500, in which the first set of transmissionparameters include at least (i) a first level of power 599-power-levelassociated with a first transmission signal 599 feeding the transmissionchain 501, and (ii) a first level of analog gain 599-gain-level asapplied by the transmission chain 501 to the first transmission signal599. In step 1042, the communication system 500 finds a first set ofpre-distortion parameters 599PDPS associated with a pre-distortionprocedure operative to counter distortions produced in conjunction withsaid first set of transmission parameters in a power amplifier 502belonging to the transmission chain 501. In step 1043, the communicationsystem 500 applies the pre-distortion procedure using the first set ofpre-distortion parameters 599PDPS, thereby at least partially counteringthe distortions.

In a first alternative to the method described above for managingpre-distortion procedures, further the communication system 500 derivesthe first set of pre-distortion parameters 599PDPS by analyzingdistortions in an output signal 599-t produced by the power amplifier502 in conjunction with said first set of transmission parameters.

In a variation of the first alternative method described above, thesystem 500 further records 521 the first set of pre-distortionparameters 599PDPS in association with the first set of transmissionparameters, for later use by the communication system 500.

In a second alternative to the method described above for managingpre-distortion procedures, further the communication system 500, usingthe first set of transmission parameters as index 521-i, searches forthe first set of pre-distortion parameters 599PDPS in a record 521associating transmission parameters with pre-distortion parameters.

In a third alternative to the method described above for managingpre-distortion procedures, further the system repeats the steps ofdetermining 1041, finding 1042, and applying procedures 1043.

In a first variation of the third alternative method described above,the repeating includes determining, by the communication system 500, asecond set of transmission parameters associated with the transmissionchain 501, and this second set of transmission parameters includes atleast (i) a second level of power 598-power-level associated with asecond transmission signal 598 feeding the transmission chain 501, and(ii) a second level of analog gain 598-gain-level as applied by thetransmission chain 501 to said second transmission signal 598. Also inthis variation, the repeating includes finding, by the communicationsystem 500, a second set of pre-distortion parameters 598PDPS associatedwith a pre-distortion procedure operative to counter distortionsproduced in conjunction with the second set of transmission parametersin the power amplifier 502. Also in this variation, the repeatingincludes applying, by the communication system 500, the pre-distortionprocedure, using the second set of pre-distortion parameters 598PDPS,thereby at least partially countering the distortions produced inconjunction with the second set of transmission parameters.

In a second variation of the third alternative method described above,further the communication system 500 concludes that the first set oftransmission parameters, previously associated with said transmissionchain 501, is no longer accurately describing a state of thetransmission chain 501, and lack of such accurate description triggersthe repeating.

In a third variation of the third alternative method described above,the repeating of steps determining 1041, finding 1042, and applyingprocedures 1043, is done periodically.

In a fourth variation of the third alternative method described above,the communication system 500 further concludes that a signal 599-tproduced by said power amplifier 502 is distorted beyond a predeterminedthreshold, thereby implying that the first set of pre-distortionparameters 599PDPS no longer correctly serve the pre-distortionprocedure, and this lack of correctly serving triggers the repeating.

In a fourth alternative to the method described above for managingpre-distortion procedures, the first set of transmission parametersfurther comprises at least one additional parameter selected from agroup consisting of: (i) a temperature associated with the poweramplifier 502, and (ii) a frequency associated with transmission chain501.

In a fifth alternative to the method described above for managingpre-distortion procedures, further the first transmission signal 599 isa base-band transmission signal.

In a variation of the fifth alternative method described above, furtherthe first level of power 599-power-level associated with the base-bandtransmission signal 599 depends, at least in part, on a level of dataresource usage associated with the base-band transmission signal 599,wherein a higher data resource usage results in a higher level of power.In one embodiment, said level of data resource usage is determined by atleast one client device served by communication system 500.

In a sixth alternative to the method described above for managingpre-distortion procedures, further the first transmission signal 599 isassociated with a communication standard selected from a groupconsisting of: (i) LTE, (ii) GSM, (iii) UMTS, (iv) CDMA, (v) WiMAX, and(vi) WiFi.

In a seventh alternative to the method described above for managingpre-distortion procedures, further the determining of said the first setof transmission parameters includes the communication system 500 settingthe first level of power 599-power-level and the first level of analoggain 599-gain-level.

In an eighth alternative to the method described above for managingpre-distortion procedures, further the determining of the first set oftransmission parameters includes the communication system 500 measuringthe first level of power 599-power-level and the first level of analoggain 599-gain-level.

In this description, numerous specific details are set forth. However,the embodiments/cases of the invention may be practiced without some ofthese specific details. In other instances, well-known hardware,materials, structures and techniques have not been shown in detail inorder not to obscure the understanding of this description. In thisdescription, references to “one embodiment” and “one case” mean that thefeature being referred to may be included in at least oneembodiment/case of the invention. Moreover, separate references to “oneembodiment”, “some embodiments”, “one case”, or “some cases” in thisdescription do not necessarily refer to the same embodiment/case.Illustrated embodiments/cases are not mutually exclusive, unless sostated and except as will be readily apparent to those of ordinary skillin the art. Thus, the invention may include any variety of combinationsand/or integrations of the features of the embodiments/cases describedherein. Also herein, flow diagrams illustrate non-limitingembodiment/case examples of the methods, and block diagrams illustratenon-limiting embodiment/case examples of the devices. Some operations inthe flow diagrams may be described with reference to theembodiments/cases illustrated by the block diagrams. However, themethods of the flow diagrams could be performed by embodiments/cases ofthe invention other than those discussed with reference to the blockdiagrams, and embodiments/cases discussed with reference to the blockdiagrams could perform operations different from those discussed withreference to the flow diagrams. Moreover, although the flow diagrams maydepict serial operations, certain embodiments/cases could performcertain operations in parallel and/or in different orders from thosedepicted. Moreover, the use of repeated reference numerals and/orletters in the text and/or drawings is for the purpose of simplicity andclarity and does not in itself dictate a relationship between thevarious embodiments/cases and/or configurations discussed. Furthermore,methods and mechanisms of the embodiments/cases will sometimes bedescribed in singular form for clarity. However, some embodiments/casesmay include multiple iterations of a method or multiple instantiationsof a mechanism unless noted otherwise. For example, when a controller oran interface are disclosed in an embodiment/case, the scope of theembodiment/case is intended to also cover the use of multiplecontrollers or interfaces.

Certain features of the embodiments/cases, which may have been, forclarity, described in the context of separate embodiments/cases, mayalso be provided in various combinations in a single embodiment/case.Conversely, various features of the embodiments/cases, which may havebeen, for brevity, described in the context of a single embodiment/case,may also be provided separately or in any suitable sub-combination. Theembodiments/cases are not limited in their applications to the detailsof the order or sequence of steps of operation of methods, or to detailsof implementation of devices, set in the description, drawings, orexamples. In addition, individual blocks illustrated in the figures maybe functional in nature and do not necessarily correspond to discretehardware elements. While the methods disclosed herein have beendescribed and shown with reference to particular steps performed in aparticular order, it is understood that these steps may be combined,sub-divided, or reordered to form an equivalent method without departingfrom the teachings of the embodiments/cases. Accordingly, unlessspecifically indicated herein, the order and grouping of the steps isnot a limitation of the embodiments/cases. Embodiments/cases describedin conjunction with specific examples are presented by way of example,and not limitation. Moreover, it is evident that many alternatives,modifications and variations will be apparent to those skilled in theart. Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and scope ofthe appended claims and their equivalents.

What is claimed is:
 1. A method for managing pre-distortion procedures,comprising: determining, by a communication system, a first set oftransmission parameters associated with a transmission chain belongingto said communication system, the first set of transmission parameterscomprising (i) a first level of power associated with a firsttransmission signal feeding said transmission chain, and (ii) a firstlevel of analog gain as applied by said transmission chain to said firsttransmission signal; finding, by said communication system, a first setof pre-distortion parameters associated with a pre-distortion procedureoperative to counter distortions produced in conjunction with said firstset of transmission parameters in a power amplifier belonging to saidtransmission chain; and applying, by said communication system, saidpre-distortion procedure, using said first set of pre-distortionparameters, thereby at least partially countering said distortions. 2.The method of claim 1, wherein said finding comprises: deriving saidfirst set of pre-distortion parameters by analyzing distortions in anoutput signal produced by said power amplifier in conjunction with saidfirst set of transmission parameters.
 3. The method of claim 2, furthercomprising: recording, by said communication system, said first set ofpre-distortion parameters in association with said first set oftransmission parameters, for later use by said communication system. 4.The method of claim 1, wherein said finding comprises: searching forsaid first set of pre-distortion parameters, in a record associatingtransmission parameters with pre distortion parameters, using said firstset of transmission parameters as index.
 5. The method of claim 1,further comprising: repeating said determining, finding, and applyingprocedures.
 6. The method of claim 5, wherein said repeating comprises:determining, by said communication system, a second set of transmissionparameters associated with said transmission chain, the second set oftransmission parameters comprising (i) a second level of powerassociated with a second transmission signal feeding said transmissionchain, and (ii) a second level of analog gain as applied by saidtransmission chain to said second transmission signal; finding, by saidcommunication system, a second set of pre-distortion parametersassociated with a pre-distortion procedure operative to counterdistortions produced in conjunction with said second set of transmissionparameters in said power amplifier; and applying, by said communicationsystem, said pre-distortion procedure, using said second set ofpre-distortion parameters, thereby at least partially countering saiddistortions produced in conjunction with said second set of transmissionparameters.
 7. The method of claim 5, further comprising: concluding, bysaid communication system, that said first set of transmissionparameters, previously associated with said transmission chain, is nolonger accurately describing a state of said transmission chain, therebytriggering said repeating.
 8. The method of claim 5, wherein saidrepeating of said determining, finding, and applying procedures is doneperiodically.
 9. The method of claim 5, further comprising: concluding,by said communication system, that a signal produced by said poweramplifier is distorted beyond a predetermined threshold, therebyimplying that said first set of pre-distortion parameters no longercorrectly serve said pre-distortion procedure, thereby triggering saidrepeating.
 10. The method of claim 1, wherein said first set oftransmission parameters further comprising at least one additionalparameter selected from a group consisting of: (i) a temperatureassociated with said power amplifier, and (ii) a frequency associatedwith said transmission chain.
 11. The method of claim 1, wherein saidfirst transmission signal is a base-band transmission signal.
 12. Themethod of claim 11, wherein said first level of power associated withsaid base-band transmission signal depends, at least in part, on a levelof data resource usage associated with said base-band transmissionsignal, wherein a higher data resource usage results in a higher levelof power.
 13. The method of claim 1, wherein said first transmissionsignal is associated with a communication standard selected from a groupconsisting of: (i) LTE, (ii) GSM, UMTS, (iv) CDMA, (v) WiMAX, and (vi)WiFi.
 14. The method of claim 1, wherein said determining of said firstset of transmission parameters comprises: setting, by said communicationsystem, said first level of power and said first level of analog gain.15. The method of claim 1, wherein said determining of said first set oftransmission parameters comprises: measuring, by said communicationsystem, said first level of power and said first level of analog gain.16. A communication system operative to manage pre-distortionprocedures, comprising: a transmission chain comprising a poweramplifier, said transmission chain is associated with a level of analoggain that is configurable by said communication system; and a modulatoroperative to feed said transmission chain with a transmission signalhaving a level of power that is configurable by said communicationsystem; wherein said communication system is operative to find, record,and use sets of pre-distortion parameters in conjunction with apre-distortion procedure, each said set of pre-distortion parametersoperative to specifically counter distortions produced in said poweramplifier by a specific combination of said level of power and saidlevel of analog gain.
 17. The system of claim 16, further comprising amemory configuration operative to facilitate recording and extraction ofsaid sets of pre-distortion parameters, each set of pre-distortionparameters in association with a specific combination of said level ofpower and said level of analog gain.
 18. The system of claim 17, whereinsaid memory configuration comprises at least a first and a secondrecord; said first record comprising: (i) a first index entry describinga combination of a first of said levels of power and a first of saidlevels of analog gain, and (ii) a first record entry describing a firstof said sets of pre-distortion parameters previously found tospecifically counter distortions produced by a specific combination ofsaid first level of power and said first level of analog gain; and saidsecond record comprising: (i) a second index entry describing acombination of a second of said levels of power and a second of saidlevels of analog gain, and (ii) a second record entry describing asecond of said sets of pre-distortion parameters previously found tospecifically counter distortions produced by a specific combination ofsaid second level of power and said second level of analog gain.
 19. Thesystem of claim 16, further comprising a distortion-analysis mechanismoperative to derive said sets of pre-distortion parameters by analyzingdistortions in an output signal produced by said power amplifier inconjunction with said specific combinations of said level of power andsaid level of analog gain.
 20. The system of claim 19, wherein saiddistortion-analysis mechanism is operative to derive a first of saidsets of pre-distortion parameters that specifically counter distortionsproduced by a specific combination of a first of said levels of powerand a first of said levels of analog gain.
 21. The system of claim 20,wherein said distortion-analysis mechanism is operative to derive asecond of said sets of pre-distortion parameters that specificallycounter distortions produced by a specific combination of a second ofsaid levels of power and a second of said levels of analog gain.
 22. Thesystem of claim 16, further comprising a pre-distortion mechanismoperative to execute said pre-distortion procedure on said transmissionsignal.
 23. The system of claim 22, further comprising at least a firstand a second processor, wherein: said modulator is a digital modulatorimplemented in a said first processor, said transmission signal is adigital base-band transmission signal generated in said digitalmodulator, and said pre-distortion mechanism is a digital pre-distortionmechanism implemented in said second processor.
 24. The system of claim23, wherein said first processor and said second processor are a sameprocessor.
 25. The system of claim 23, wherein said first processor andsaid second processor are digital-signal-processors.
 26. The system ofclaim 16, wherein said transmission signal is a base-band transmissionsignal, and said transmission chain further comprising an up-converteroperative to up-convert said base-band transmission signal into atransmission frequency associated with said power amplifier.
 27. Thesystem of claim 16, wherein said transmission chain further comprisingan antenna, operative to transmit wirelessly an output signal producedby said power amplifier in conjunction with said transmission signal.